Rotary lamination apparatus

ABSTRACT

A rotary lamination apparatus has a die assembly rotatable about an axis and a mounting table received in an axial hole extending through the die assembly. Through rotation of the die assembly, punched core pieces are mounted on the mounting table while being rotatively offset. A drive portion is employed to rotate the mounting table integrally with the die assembly about the axis of the die assembly.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 13/186,972filed Jul. 20, 2011, and which claims priority to Japanese ApplicationNo. 2010-194063, filed Aug. 31, 2010, the disclosures of which areexpressly incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for manufacturing a corefor a rotational electric machine, such as a stator core or a rotor corefor a motor, and, more particularly, a rotary lamination apparatus thatlaminates core pieces punched from thin plates, while rotativelyoffsetting the core pieces.

A core WA shown in FIGS. 6 and 7 is formed by layering core pieces Wa.The core WA is maintained in a layered state through engagement betweena plurality of projections Pa of each of the core pieces Wa and adjacentrecesses of the core piece Wa.

An apparatus for manufacturing this type of core is disclosed in, forexample, Japanese Laid-Open Patent Publication No. 2006-26735 (firstconventional art) and Japanese Laid-Open Patent Publication No.2003-19520 (second conventional art).

In the first conventional art, a punch is arranged above and faces a diein a manner movable in the axial direction. As the punch reciprocateswith respect to the die, a core piece is punched out from a thin platemounted on the die. A pressing ring is arranged below the die. An axialhole extends through the centers of the die and the pressing ring, andreceives a mounting table, which is movable in the axial direction ofthe die. After having been punched using the punch and the die, a corepiece is pressed and held by the pressing ring from the outercircumference. The core piece is then mounted on the mounting table andsubsequent core pieces are sequentially layered on the core piece. Acore is thus manufactured. When a punched core piece is mounted on themounting table, an elastic member arranged on the mounting table appliesforce acting in the opposite direction to the direction in which thepunch presses, or counter pressure, to the laminated core. This preventsparallelism defect and formation of gaps between layers.

In the second conventional art, a die is rotatable. Each time a singlecore piece or a predetermined number of core pieces are punched by apunch and the die, the die and a pressing ring are rotated integrallywith the core piece(s) at a predetermined angle. Through such rotationof the die and the pressing ring, the core pieces are layered whilebeing rotatively offset, with offset phases. This prevents thelamination thickness of a laminated core from becoming non-uniform dueto thicknesses deviation of punched core pieces.

However, the above-described conventional configurations have theproblems described below.

In the first conventional art, core pieces are stacked on the mountingtable in a constant phase (orientation) without being rotated afterhaving been punched out. This causes a non-uniform lamination thicknessin a laminated core, which is brought about by thicknesses deviation ofthe core pieces. Accordingly, if a rotor core for a motor, for example,is manufactured, rotation accuracy such as rotation balance is decreasedand thus the motor characteristics are deteriorated.

In contrast, in the second conventional art, the core pieces are layeredwhile being rotatively offset through rotation of the die and thepressing ring. The problem caused by the first conventional art is thusprevented. However, the second conventional art does not include amounting table that applies the counter pressure to a laminated core. Asa result, unlike the first conventional art, the second conventional artcannot prevent parallelism defect of the laminated core or gap formationbetween layers.

Alternatively, in an apparatus having a rotatable die and a rotatablepressing ring like those from the second conventional art, a mountingtable may be arranged in an axial hole formed in the die, as in thefirst conventional art. However, in this configuration, core pieces aremounted on the mounting table while being rotatively offset throughrotation of the die and the pressing ring with the mounting table heldin a stationary state without being rotated. This rotates a laminatedcore formed on the mounting table relative to the mounting table,causing the core and the table to rub against each other. This may forman abrasion mark on a core piece. Also, when a core is already mountedon the mounting table and an additional core piece is mounted on theuppermost core piece of the core while being rotatively offset, theupper and lower cores rotate relative to each other, causing projectionsPa to form a clear linear abrasion mark on the cores. The abrasion markmay influence formation of magnetic paths, thus lowering the performanceof the products.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide arotary lamination apparatus capable of preventing abrasion between alaminated core and a mounting table when the laminated core is formed byrotatively offsetting and mounting core pieces on the mounting tablethrough rotation of a die assembly, thereby preventing performance of aproduct from deteriorating.

To achieve the foregoing objective and in accordance with one aspect ofthe present invention, a rotary lamination apparatus for layeringpunched out core pieces while rotatively offsetting the core pieces isprovided. The apparatus includes a die assembly having a die, a mountingtable, and a drive portion. The die assembly has an axial hole and anaxis, and is rotatable about the axis. The mounting table is received inthe axial hole of the die assembly. The core pieces are layered whilebeing rotatively offset on the mounting table through rotation of thedie assembly. The drive portion rotates the mounting table integrallywith the die assembly about the axis of the die assembly.

Other aspects and advantages of the present invention will becomeapparent from the following description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a cross-sectional view showing a main portion of a rotarylamination apparatus according to a first embodiment of the presentinvention;

FIG. 2 is a partially cross-sectional view taken along line 2-2 of FIG.1;

FIG. 3 is a cross-sectional view showing a main portion of a rotarylamination apparatus according to a second embodiment of the presentinvention;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a cross-sectional view showing a main portion of a rotarylamination apparatus according to a third embodiment of the presentinvention;

FIG. 6 is a perspective view showing a core; and

FIG. 7 is a cross-sectional view showing a portion of the core.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A rotary lamination apparatus according to a first embodiment of thepresent invention will now be described with reference to FIGS. 1 and 2.

As illustrated in FIG. 1, the rotary lamination apparatus includes aholding member 11, which is rotatable about a vertical axis C. Theholding member 11 is rotated intermittently by a predetermined angle ata time by a non-illustrated motor. An annular die 12 is fixedly attachedto the upper inner circumferential edge of the holding member 11. Apunch 13 is arranged above the die 12 and can be reciprocated along thevertical axis C. With a belt-like thin plate W mounted on the holdingmember 11, the punch 13 is reciprocated in an upward-downward directionwith respect to the die 12. In this manner, a core piece Wa having aprescribed shape is punched out of the thin plate W.

A cylindrical pressing ring 14 is fixedly attached to the innercircumference of the holding member 11 at a position below the die 12.The pressing ring 14 applies pressure to the outer circumferentialsurface of the core piece Wa after the core piece Wa has been punchedout. The holding member 11 and the pressing ring 14 form a die assembly10.

An axial hole extends through the die assembly 10 accommodates amounting table 15, which is movable along the vertical axis C. Afterhaving been punched out by the punch 13 and the die 12, core pieces Waare pressed and held by the pressing ring 14 from the outercircumference and mounted and layered sequentially on the mounting table15. At this time, the die assembly 10 is rotated by the non-illustratedmotor, and the die 12 and the pressing ring 14 are rotated integrallywith the holding member 11. As a result, with the thin plate W on theholding member 11 maintained without rotating, the punched core piecesWa are layered while being rotatively offset on the mounting table 15.This forms a laminated core WA for a rotating electric machine, such asa stator core or a rotor core for a motor.

In this case, when a punched core piece Wa is mounted on the mountingtable 15, a lift mechanism 16 including a motor raises the mountingtable 15 through a shaft 17. This applies counter pressure acting in theopposite direction to the pressing direction of the punch 13 to thelaminated core WA on the mounting table 15. At this stage, the topsurface of the uppermost core piece Wa on the mounting table 15 islocated flush with the top surface of the die 12.

The mounting table 15 has a support member 18 and a receiving table 21.The support member 18 is fixed to the upper end of the shaft 17. Thereceiving table 21 is arranged above the support member 18 and supportedrotatably about the vertical axis C through a radial bearing 19 andthrust bearings 20. A holding plate 23 is mounted on the receiving table21 through a thrust bearing 22 in a manner rotatable relative to thereceiving table 21. The holding plate 23 is fixed to the support member18 by means of a plurality of bolts 24. The receiving table 21 is thusheld by the support member 18 and is prevented from separating from thesupport member 18. Core pieces Wa are mounted on the receiving table 21.A sensor 23 a for detecting a core piece Wa on the receiving table 21 isinstalled on the holding plate 23.

A drive mechanism 25 serving as drive means or a drive portion isarranged in the vicinity of the mounting table 15 to rotate the mountingtable 15 integrally with the die 12 about the vertical axis C of the dieassembly 12. In the first embodiment, the drive mechanism 25 isconfigured by the die assembly 10. A transmission mechanism 26 servingas transmission means is arranged between the holding member 11 and themounting table 15 to transmit rotation of the holding member 11 to themounting table 15.

The transmission mechanism 26 is arranged between the innercircumferential surface of the holding member 11 and the outercircumferential surface of the mounting table 15. The transmissionmechanism 26 is configured by meshing means or a meshing mechanism thatpermits axial movement of the mounting table 15. Specifically, innerspline teeth (hereinafter, referred to simply as internal teeth) 27 areformed on the inner circumferential surface of the holding member 11.External spline teeth (hereinafter, referred to simply as externalteeth) 28, which become meshed with the corresponding internal teeth 27in an axially movable manner relative to the internal teeth 27, areformed on the outer circumferential surface of the receiving table 21 ofthe mounting table 15. The transmission mechanism 26 is configured bythe internal teeth 27 and the external teeth 28. When the die assembly10 is rotated to rotate the die 12 and the pressing ring 14 integrally,the receiving table 21 of the mounting table 15 is rotated integrallywith the die assembly 10 through the internal teeth 27 and the externalteeth 28 of the transmission mechanism 26.

The rotary lamination apparatus, which is configured as has beendescribed, operates as described below.

With the thin plate W held on the holding member 11, the punch 13 isreciprocated with respect to the die 12, thus punching a core piece Wahaving a prescribed shape out of the thin plate W. After having beenpunched out, core pieces Wa are pressed and held by the pressing ring 14from the outer circumference, and mounted and sequentially layered onthe receiving table 21 of the mounting table 15. In this case, in thetransmission mechanism 26, the external teeth 28 of the receiving table21 are axially moved relative to the internal teeth 27 of the holdingmember 11 to permit descent of the mounting table 15, and the liftmechanism 16 raises the mounting table 15 through the shaft 17, thusapplying counter pressure acting in the opposite direction to thepressing direction of the punch 13 to a laminated core WA on themounting table 15.

Each time a single core piece Wa or a predetermined number of corepieces Wa are punched out, the die assembly 10 is rotated integrallywith the holding member 11 at a predetermined angle. In this manner,core pieces Wa are layered while being rotated with offset phases, and alaminated core WA is formed. This prevents the lamination thickness ofthe laminated core WA from becoming non-uniform due to thicknessesdeviation of punched core pieces Wa.

Further, when core pieces Wa are layered while being rotatively offsetfrom each other on the receiving table 21 of the mounting table 15through rotation of the die assembly 10, rotation of the die assembly10, which is a component of the drive mechanism 25, is transmitted tothe receiving table 21 of the mounting table 15 through the transmissionmechanism 26. This rotates a laminated core WA on the receiving table 21integrally with the mounting table 15. As a result, the laminated coreWA on the mounting table 15 and the mounting table 15 are prevented fromrubbing against each other. Also, when a laminated core WA is maintainedon the mounting table 15 and another core WA is laminated on the core WAwhile being rotatively offset, the cores CA do not rub against eachother. The pitch of a single cycle of intermittent rotation of the dieassembly 10 and the mounting table 15 is equal to the alignment pitch ofthe projections Pa of the core pieces Wa.

After a predetermined number of core pieces Wa are layered on themounting table 15 in the above-described manner, the mounting table 15is lowered below the position indicated by the lines formed by a longdash alternating with two short dashes in FIG. 1, to a position downwardfrom the holding member 11. When the mounting table 15 is located atthis position, the core WA is transferred from the mounting table 15 fora subsequent step.

The first embodiment has the advantages described below.

(1) The drive mechanism 25 is provided to rotate the mounting table 15integrally with the die assembly 10 about the axis of the die assembly10.

Accordingly, each time a core piece Wa is punched out, the die assembly10 is rotated at a predetermined angle. Through rotation of the dieassembly 10, core pieces Wa are layered while being rotated with offsetphases on core pieces Wa on the mounting table 15, and a laminated coreWA is formed. This prevents the lamination thickness of the laminatedcore WA from becoming non-uniform due to thicknesses deviation ofpunched core pieces Wa. Also, when a punched core piece Wa is mountedwhile being rotatively offset on the mounting table 15 through rotationof the die assembly 10, the drive mechanism 25 rotates the mountingtable 15 integrally with the die assembly 10 about the axis of the dieassembly 10. This prevents the core piece Wa and the mounting table 15or another core piece Wa from rubbing against each other. The corepieces Wa are thus protected against abrasion marks. As a result, a coreWA that has a uniform lamination thickness and is free from abrasionmarks is obtained. In this manner, cores WA with improvedcharacteristics are manufactured.

(2) The drive mechanism 25 is configured by the die assembly 10 havingthe die 12. The transmission mechanism 26 for transmitting rotation ofthe die assembly 10 to the mounting table 15 is arranged between the dieassembly 10 and the mounting table 15. As a result, using the rotationof the die assembly 10, the mounting table 15 is rotated integrally withthe die assembly 10. In other words, the mounting table 15 is rotated bya simple structure.

(3) The transmission mechanism 26 is arranged between the die assembly10 and the outer circumferential surface of the mounting table 15, andconfigured by the meshing means that permits axial movement of themounting table 15. In other words, the transmission mechanism 26 isconfigured to be simple and capable of transmitting rotation of the dieassembly 10 to the mounting table 15 accurately without loss.

Second Embodiment

A rotary lamination apparatus according to a second embodiment of thepresent invention will hereafter be described with reference to FIGS. 3and 4, mainly discussing the differences between the second embodimentand the first embodiment.

The second embodiment has a drive mechanism 25 configured by a dieassembly 10 including a die 12, a pressing ring 14, and a holding member11, like the first embodiment. However, in the second embodiment, atransmission mechanism 26 is configured differently from thetransmission mechanism 26 of the first embodiment.

Specifically, in the transmission mechanism 26 of the second embodiment,a tubular portion 31 is arranged below the receiving table 21 of themounting table 15 and extends in the axial direction. A guide 32 formedby sets of engaged projections and recesses is formed along the outercircumference of the tubular portion 31, extending in the axialdirection. A spring seat 33 is formed along the lower outercircumferential edge of the tubular portion 31. An annular slider 34 issupported by the outer circumference of the tubular portion 31 throughthe guide 32 in such a manner that the slider 34 is rotatable integrallywith the tubular portion 31 and movable relative to the tubular portion31 in the axial direction.

A joint member 35 having a plurality of teeth that are aligned annularlyis arranged at the lower inner circumferential edge of the holdingmember 11. A joint member 36 also including a plurality of teeth alignedin an annular shape is deployed at the upper outer circumferential edgeof the slider 34. The joint members 35, 36 are meshed with each other. Aplurality of springs 37 are arranged between the slider 34 and thespring seat 33. The springs 37 urge the slider 34 upward to maintainconstant meshing between the joint members 35, 36. The die assembly 10is thus rotated at constant angular intervals. When a core piece Wa ismounted on the receiving table 21 of the mounting table 15 while beingrotatively offset, rotation of the die assembly 10 is transmitted to thereceiving table 21 through the joint members 35, 36, the slider 34, theguide 32, and the tubular portion 31. The laminated core WA on thereceiving table 21 is thus rotated integrally with the receiving table21.

In the second embodiment, when the mounting table 15 is lowered, thetubular portion 31 below the receiving table 21 is moved through theguide 32 relative to the slider 34 in the axial direction. In thisstate, the slider 34 is maintained at a constant position by the urgingforce generated by the springs 37. This maintains the joint members 35,36 in the engaged state, thus ensuring continuous transmission of therotation to the mounting table 15.

As a result, the second embodiment ensures the advantages that aresubstantially the same as the advantages (1) to (3) of the firstembodiment.

Third Embodiment

A rotary lamination apparatus according to a third embodiment of thepresent invention will hereafter be described with reference to FIG. 5,mainly discussing the differences between the third embodiment and thefirst embodiment.

The third embodiment is different from the first embodiment in theconfiguration of a drive mechanism 25, which rotates a mounting table15. Specifically, a servomotor 38 having a decelerator 39, whichconfigures the drive mechanism 25, is arranged outside and below asupport member 18 of the mounting table 15 in such a manner that theservomotor 38 is movable integrally with the support member 18 in anupward-downward direction. A drive gear 41 configured by external teethis fixed to a rotary shaft 40 of the servomotor 38. A driven gear 42configured by internal teeth, which can mesh with the drive gear 41, isfixed to the lower end of the receiving table 21 of the mounting table15.

The die assembly 10 is rotated at constant angular intervals. When acore piece Wa is mounted on the receiving table 21 of the mounting table15 while being rotatively offset, the servomotor 38 is rotatedsynchronously with the die assembly 10. This rotates the receiving table21 through the drive gear 41 and the driven gear 42. The laminated coreWA on the receiving table 21 is thus rotated integrally with the dieassembly 10.

The third embodiment has the advantage described below in addition tothe advantage (1) of the first embodiment.

(4) The drive mechanism 25 is configured by the servomotor 38, whichrotates the mounting table 15 synchronously with the die assembly 10. Asa result, a rotary lamination apparatus operating in the same manner asthe third embodiment is provided simply by slightly modifying aconventional rotary lamination apparatus and adding the servomotor 38 tothe apparatus.

Modifications

The present invention may be embodied in the modified forms describedbelow.

The invention may be embodied as a rotary lamination apparatus withoutthe pressing ring 14.

In the third embodiment, the servomotor 38 may be installed at aposition spaced from the mounting table 15. A drive force transmissionmechanism such as a gear is arranged between the servomotor 38 and themounting table 15.

Therefore, the present examples and embodiments are to be considered asillustrative and not restrictive and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

1. A rotary lamination apparatus for layering punched out core pieceswhile rotatively offsetting the core pieces, the apparatus comprising: adie assembly that has an axial hole and an axis, and is rotatable aboutthe axis, the assembly having a die; a mounting table received in theaxial hole of the die assembly, wherein the core pieces are layeredwhile being rotatively offset on the mounting table through rotation ofthe die assembly; and a drive portion that rotates the mounting tableintegrally with the die assembly about the axis of the die assembly,wherein the drive portion includes a motor that rotates the mountingtable synchronously with rotation of the die assembly.